I'm using a Canon Power Shot SC30IS. By natural light I mean it's in the house but our house has many windows and a lot of natural light. I also have a Ottlight that I use plus a fluorescent lamp, if the lighting is too dark. I never use a flash.

You say natural lighting. Did you take a picture of this painting outside in the daylight? You said natural lighting ( for the most part ). What is the other part. Did you a flash? Did you use added lighting? I take it your using a digital camera? Does your camera automaticlly ajust for the shot when you hold the shutter butten haft way down. Do you find the images shot of your other paintings lacking in color, tone and or contrast? Did you take photographs of the rest of you panting in the same manner or fashion as you did this one. These factor and more and the manner in which they were used add to the out come of this image of your painting. By answering this question I will be albe to solve the question why this image looks this way.

Tell me about how and where you captured the images of your painting. Scanned, camera, lighting ,setting...........etc. Here are many things you can do to bring out the natural color and contrast in paintings. It help me to help you better if I know the way you have been capturing your images